A marketing firm determined that, of 200 households surveyed, 80 used neither Brand A nor Brand B soap, 60 used only Brand A soap, and for every household that used both brands of soap, 3 used only Brand B soap. How many of the 200 households surveyed used both brands of soap?
(A)15 (B)20 (C)30 (D)40 (E)45
Jessie
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anyone can help me? I am not sure if there is an answer in the question.
- dominic
I believe the answer is A. 200 - 80 (households that use neither) = 120. 120 - 60 (used only A) = 60. 60/4 (1 for dual users and 3 for B only) = 15.
- Soup in a TARDIS
I agree with Soup.
- OCoG of FF, Jimminy
yes, it's the answer. but how did you know " for every household that used both brands of soap, 3 used only Brand B soap" is "1 for dual users and 3 for B only"? did households have four people?
- dominic
it's the problem of the question that I misunderstand the sentence, I think.
- dominic
You start with a set of 200 people who use soap. 80 don't use either brand. 60 use Brand A. The remaining group of 60 people, either uses Brand B or both Brands A & B. Of the remaining people the ratio is 3(Brand B exclusively) to 1(Brands A&B). So those that use brand B is 3/4 and both is 1/4.
- OCoG of FF, Jimminy
200 = N + A + B + Z; N = 80; A = 60; B = 3Z (where N = neither, A = brand A, B = brand B, Z = both)
- Jim Norris
Thank you all. I got it now. I understand the descrpition of the ratio like this.
- dominic